What does the first cartridge loaded into a magazine press against?

The first cartridge loaded into a magazine presses against the follower. The follower is a crucial component within the magazine that helps to keep the cartridges properly stacked and positioned, allowing for reliable feeding into the firearm's chamber as the action cycles. When the first cartridge is inserted, it pushes against the follower, which in turn is pushed upwards by the magazine spring. This interaction ensures that the cartridges maintain their correct alignment and are available to be fed into the firearm when it is fired.

The follower's design and functionality are essential for smooth operation, as a malfunctioning follower can lead to feed issues or jams. This highlights the importance of the follower in maintaining the overall reliability and safety of the firearm during operation.